CVE-2026-100844
Received Received - Intake

OS Command Injection in MONAI nnUNetV2Runner

Publication date: 2026-09-27

Last updated on: 2026-09-27

Assigner: VulnCheck

Description
MONAI before 1.6.0 is vulnerable to OS command injection in the nnUNetV2Runner component (monai.apps.nnunet.nnunetv2_runner). User-controlled values taken from the YAML configuration file (notably dataset_name_or_id) and from CLI/kwargs arguments are concatenated into a command string without quoting or validation and then passed to subprocess with shell=True, so shell metacharacters (e.g., ';' on Linux, '&' on Windows) are interpreted. If a victim loads and processes a crafted configuration file — for example by instantiating nnUNetV2Runner with the malicious YAML and invoking a training/validation job such as train_single_model() — arbitrary commands are executed with the privileges of the user running the job.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-27
Last Modified
2026-09-27
Generated
2026-09-27
AI Q&A
2026-09-27
EPSS Evaluated
N/A
NVD
CVE-2026-100844
EUVD
EUVD-2026-87844

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
monai monai to 1.6.0 (exc)
project_monai monai to 1.6.0 (exc)

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-78 The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

CVE-2026-100844 is an OS command injection vulnerability in MONAI versions before 1.6.0. It occurs in the nnUNetV2Runner component where user-controlled values from YAML files or CLI arguments (like dataset_name_or_id) are concatenated into a command string without validation or quoting. This command is then executed via subprocess with shell=True, allowing attackers to inject shell metacharacters (e.g., ; or &) to execute arbitrary commands with the privileges of the running process.

Detection Guidance

Check MONAI version with pip show monai. If version is 1.5.1 or earlier, the system is vulnerable. Inspect YAML files for dataset_name_or_id fields containing shell metacharacters like ; or &. Monitor subprocess calls in logs for unexpected command execution patterns.

Impact Analysis

This vulnerability allows attackers to execute arbitrary commands on your system if you process a crafted YAML configuration file in MONAI versions before 1.6.0. This could lead to unauthorized access, data theft, system compromise, or disruption of services. The attack requires no special privileges or user interaction beyond loading the malicious file.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, violating GDPR and HIPAA requirements for data protection and confidentiality. Organizations using affected MONAI versions may face compliance violations, legal penalties, and reputational damage if exploited.

Mitigation Strategies

Upgrade MONAI to version 1.6.0 or later immediately. Avoid loading untrusted YAML files in nnUNetV2Runner. Validate all user-controlled inputs before passing to subprocess. Disable shell=True in subprocess calls if possible.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-100844. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart